Prognosis in patients with aortic regurgitation is usually determined by the status of left ventricular (LV) function. However, when death occurs, it is often sudden and may be arrhythmogenic in origin. The present study utilized 24-hour ambulatory monitoring to evaluate 133 consecutive patients with isolated aortic regurgitation for the occurrence of ventricular arrhythmias. The frequency and severity of the ventricular arrhythmias that were detected correlated with measurements of LV dimensions or function, and exercise capacity. Asymptomatic patients had a lower frequency of ventricular ectopic beats and less high grade ventricular events (two or more in a row) compared to symptomatic patients before operation and patients who had had their aortic valves replaced. There was no difference in the frequency or severity of arrhythmias between the latter two groups. Those patients in the synmptomatic and operated groups who had high grade and increased frequency of arrhythmias had depressed rest and exercise LV function compared to patients in those groups without high grade arrhythmias. In addition, patients with high frequency and grade arrhythmias also had larger LV dimensions. Exercise capacity was similar in patients with low and high grade arrhythmias. During a mean follow-up time just over three years, there have been 10 deaths in these patients, but only two of them could be attributed to ventricular arrhythmias. This work demonstrates that increased frequent and grade of ventricular ectopy is common in patients with aortic regurgitation and appears to be related to LV dysfunction. The ventricular ectopy did not appear to be related to the occurrence of sudden death, although chronic antiarrhythmic therapy may have had a protective effect and contributed to the low mortality. Also follow-up time was relatively short.